The present invention relates to a crystal oscillator controlled stepping motor.
Typically, stepping motor devices include a pivotal electrodynamically movable drive member that meshes at least indirectly by means of an indexing member with an indexing wheel and progressively drives the wheel ahead step-by-step.
In recent years, stepping motors have been used in electronic watches to drive the time indicating hands of the watch. These watches, however, are sensitive to shocks and accelerations which can index the stepping motor by one step, and under most adverse conditions even by several steps, causing the watch to run fast. A shock during the indexing moment, taking effect in a direction opposite to that of the drive, may cause the failure of an indexing step to take place causing the watch to run slow.
The following patents represent some of the prior art pertinent to the field of the present invention: U.S. Pat. Nos. 3,766,729 issued Oct. 23, 1973; 3,795,097 issued Mar. 5, 1974; 3,887,825 issued June 3, 1975; 3,509,437 issued Apr. 28, 1970; 3,818,690, issued June 25, 1974; 3,163,808 issued Dec. 29, 1974; 3,568,017 issued Mar. 2, 1971; and 3,896,363 issued July 22, 1975.
These patents are mentioned as being representative of the prior art and other pertinent patents may exist. None of the above cited patents are deemed to affect the patentability of the present invention.